Project BMW 325is Part 7: VDO gauge console from BMP Design

When at the dragstrip for testing, trying to determine whether Project 325 had cooled down for another quarter-mile run, I decided I needed some gauges. Real gauges, with real numbers on them. An idiot light and a blue zone followed by a red zone indicating a probable need for engine replacement are no substitute for actual numbers.

BMP Design is one of several companies marketing a gauge panel to replace the E36's factory sunglass holder. Like others, its standard kit includes oil pressure, oil temperature and electrical system voltage. BMP uses VDO Vision Design electrical instruments, which I like. Many aftermarket instruments look like they should be hose-clamped to the steering column of an El Camino, but VDO gauges look just like the factory instruments in the last four decades of Porsches, because that's what they are.

Electrical system voltage is less important to me than coolant temperature, which was the impetus for this whole task. The factory gauge indicates normal when the car is just warmed up and stays at normal until it's really hot. At my request, BMP built a console just for Project 325 with a water temperature gauge in place of the voltage gauge.

I thought it would be fairly easy to install the gauges, based on the instructions, but it took me about 18 hours. I also added features, installing Rogue Engineering adapters and VDO senders in the transmission and differential and wiring a switch to change the oil temperature reading between engine, trans and diff. I'm anal and take the time to be sure things are done as well as possible, but this job was seriously a pain. You'll have to drain some or all of the liquid from whatever systems' temperatures you are measuring, which meant I changed engine, trans and diff lubes as well as drooling out some BMW blue coolant. If you're using synthetics, you may want to plan farther ahead than I did or save it for the next change interval.

Factory wiring is very well integrated. It's protected from mechanical damage and hidden from view. Running most of the gauge wires where they would go in an ideal world would mean disassembling much of the vehicle, so I ended up running wires where they weren't meant to be. To get away with that, I had to armor the heck out of them, but I still ended up with zip ties and funky colors all over the place under the car. It's less than ideal in some respects, but now I can properly monitor the driveline, which is better than before. Over the last few months, I've also been working on horsepower and further refining the suspension. Those are being sorted out gradually, and the results are promising.